16 February 2024 | Petru P. Albertini, Mark A. Newton, Min Wang, Ona Segura Lecina, Philippe B. Green, Dragos C. Stoian, Emad Oveisi, Anna Loiudice, Raffaella Buonsanti
This study introduces a novel approach to synthesize hybrid organic/inorganic materials, specifically copper nanocrystals (Cu NCs) encapsulated in an amorphous alumina shell with embedded organic ligands. The hybrid coating is designed to enhance the stability and activity of Cu catalysts during the electroreduction of CO₂ (CO₂RR). The Cu NCs are functionalized with trioctylamine and tetradecylphosphonic acid ligands, and the alumina shell is grown using a colloidal atomic layer deposition (c-ALD) method. The thickness of the alumina shell can be tuned by varying the number of c-ALD cycles, which affects the structural stability and selectivity of the catalysts.
The Cu@AlOx NCs exhibit improved stability against structural reconstruction compared to bare Cu NCs, as evidenced by their retention of initial morphology and preferential methane selectivity during CO₂RR. The structural stability is attributed to the locking of a fraction of the copper surface into a Cu²⁺ state, which inhibits redox processes responsible for structural reconstruction. The Lewis acidity of the alumina shell, which transitions from Bronsted to Lewis acidity with increasing shell thickness, also plays a crucial role in maintaining the structural stability.
Operando X-ray absorption spectroscopy (XAS) reveals that the Cu@AlOx NCs maintain a higher fraction of Cu²⁺ during operation, contributing to their enhanced stability. The intrinsic activity of the Cu@AlOx NCs is twice that of bare Cu NCs, with a fivefold increase in methane production. The selectivity can be manipulated by changing the electrolyte, demonstrating the potential for tuning the catalyst's performance.
Overall, the study provides a new platform for designing stable and active electrocatalysts for CO₂RR, with potential applications in sustainable energy conversion and chemical production.This study introduces a novel approach to synthesize hybrid organic/inorganic materials, specifically copper nanocrystals (Cu NCs) encapsulated in an amorphous alumina shell with embedded organic ligands. The hybrid coating is designed to enhance the stability and activity of Cu catalysts during the electroreduction of CO₂ (CO₂RR). The Cu NCs are functionalized with trioctylamine and tetradecylphosphonic acid ligands, and the alumina shell is grown using a colloidal atomic layer deposition (c-ALD) method. The thickness of the alumina shell can be tuned by varying the number of c-ALD cycles, which affects the structural stability and selectivity of the catalysts.
The Cu@AlOx NCs exhibit improved stability against structural reconstruction compared to bare Cu NCs, as evidenced by their retention of initial morphology and preferential methane selectivity during CO₂RR. The structural stability is attributed to the locking of a fraction of the copper surface into a Cu²⁺ state, which inhibits redox processes responsible for structural reconstruction. The Lewis acidity of the alumina shell, which transitions from Bronsted to Lewis acidity with increasing shell thickness, also plays a crucial role in maintaining the structural stability.
Operando X-ray absorption spectroscopy (XAS) reveals that the Cu@AlOx NCs maintain a higher fraction of Cu²⁺ during operation, contributing to their enhanced stability. The intrinsic activity of the Cu@AlOx NCs is twice that of bare Cu NCs, with a fivefold increase in methane production. The selectivity can be manipulated by changing the electrolyte, demonstrating the potential for tuning the catalyst's performance.
Overall, the study provides a new platform for designing stable and active electrocatalysts for CO₂RR, with potential applications in sustainable energy conversion and chemical production.